In order to properly allocate online content for sponsorship when presented via an information portal, such as search engines, conventional portals auction each slot or position on such content to a highest ranking bidder (e.g., an advertiser or agent). Rank may be determined in terms of bidden dollar amount or by a weighted value computed from various factors, including a click-through rate or expected click percentage. Typically, a user submitting a query to a search engine invokes an auction for positions on the page returned by the query. Bidders offer to pay a price up to a specific amount for positions or slots; successful bids result in a search page displaying advertisements alongside ordinary search results for the query.
To illustrate one example, under a Generalized Second Price (GSP) auction, after an advertiser places a single bid, the bids are ranked by weight such that weighted bids determine the slot allocation. Most search engines typically take a two-pronged approach to the above auction: (1) find relevant advertisements for a query, and (2) estimate a click-through rate for the retrieved advertisements, apply an appropriate weight to each bid and allocate multiple slots for displaying those advertisements (one for each advertisement) on the search page. The slots are ordered and higher slots may be more valuable in terms of the click-through rate. For example, a top slot normally may receive twenty clicks per thousand impressions while a next-highest slot may receive ten clicks. Achieving an optimal assignment of slots has proven to a difficult and costly undertaking. This is especially true when taking into account the relatively short time frame within which the search page is typically displayed in response to the query.